Wire connector

ABSTRACT

A wire connector in which installation torque is transmitted from an insulating housing to a tapered spring connector member contained within a cavity in the housing through threaded engagement between a convolution at the smaller end of the spring member and the housing at the corresponding end of the cavity.

United States Patent Waddington et 21.

Apr. 1, 1975 [54] WIRE CONNECTOR FOREIGN PATENTS OR APPLICATIONS 1 1lnvemorsl William Waddington, Faflwood; 777,950 2/1968 Canada 174/87Charles F. Mazzeo, Scotch Plains, both of N]. L C PrimaryExaminer-Darrell lay [73 1 Asslgnee' fi v Corporatmn New York Attorney,Agent, or Firm-Samuelson & Jacob [22] Filed: May 31, 1973 21 Appl. No.:365,548 1571 ABSTRACT A wire connector in which installation torque istrans- [52] U.S. Cl. 174/87, 403/18 mitted from an insulating housing toa tapered spring [51] Int. Cl H01r 5/12, HOZg 15/08 connector membercontained within a cavity in the [58] Field of Search 174/87, 138 F;287/75, housing through threaded engagement between a con- 287/78;403/18 volution at the smaller end of the spring member and the housingat the corresponding end of the cavity. [56] References Cited UNITEDSTATES PATENTS 1 Claim, 4 Drawing Figures 3.519 707 7/1970 Krup 174/87 RWIRE CONNECTOR The present invention relates generally to wireconne'ctors for securing a connection between electrical wire ends byrotational installation of the connector over the wire ends andpertains, more specifically, to a wire connector in which installationtorque is transmitted from an insulating housing to a tapered springconnector member contained within a cavity in the housing throughthreaded engagement between the spring member and the housing.

Wire connectors have proved to be highly effective in providing a simplemeans for securing electrical wires together, both mechanically andelectrically, in many different installations and have gained a highdegree of commercial acceptance. As a result. a wide variety of suchdevices has been developed in an effort to simplify their design andconstruction while increasing their operating effectiveness. In suchdevices, the wires are connected by a tapered, helically coiled springmember contained within a housing of insulating material having a closedend such that the connection is insulated electrically. The device isturned onto the ends of the wires with installation torque beingtransmitted from the housing to the spring member. With some existingconnectors. it is possible to make a connection which is unsafe andactually hazardous. In particular, in connecting solid wires where thewire ends are not precisely aligned longitudinally with one another. thefollowing several distinct hazardous conditions can occur.

First, the electrical wires can be threaded into the connector with suchforce that the wire which is advanced longitudinally further than theremaining wires can actually drill through the insulation material ofthe housing at the closed end.

Second, the wires can be threaded into the connector with sufficientforce so that the furthest advanced wire strikes the closed end of thehousing. Ifthe closed end of the housing resists penetration of thewire, and if additional torque is applied, the wire can act like a screwand the spring member can act like a nut, thus developing a force thatcan drive the spring member in the direction away from the closed end ofthe housing toward the open end. Unless there is a sufficiently strongsupplementary means for retaining the spring member inside the housing.the spring member can partially back out of the housing. creating ahazardous condition.

Third. with only one or two convolutions of the spring member grippingthe wires. the furthest advanced wire can strike the non-resistantclosed end of the housing. Continued rotation of the connector willcause movement of the spring member away from the closed end of thehousing thereby disengaging the driving coupling between the housing andthe spring member and leaving only a limited connection between thespring member and the wires. A strong pull on either wire could pull thewire from the connector.

It is therefore an object of the invention to provide a wire connectorwhich overcomes the above limitations and thus precludes the occurrenceof the hazardous conditions outlined above.

Another object of the invention is to provide a wire connector with animproved coupling arrangement between the spring member and the housingof the connector for transmitting installation torque from the housingto the spring member.

Still another object of the invention is to provide a wire connector inwhich considerable torque can be applied to the connection between wireswithout slippage between the housing and the spring member of theconnector.

A further objectof the invention is to provide a wire connector with asimplified construction having component parts which are easy tomanufacture. assemble and use.

The above objects, as well as still further objects and advantages. areattained by the invention which may be described briefly as a wireconnector for securing a connection between electrical wire ends byrotational installation over the wire ends, the wire connectorcomprising a helically coiled spring member extending longitudinallyfrom a larger diameter first end toward a smaller diameter second end,the spring member being generally tapered longitudinally along a centralportion between the ends thereof and having a plurality of convolutions,and a housing of relatively rigid insulating material, the housinghaving a cavity containing the spring member, the cavity having aconfiguration generally complementary to the external configuration ofthe spring member with the relative dimensions of the cavity and thespring member providing a clearance space between the housing and thecentral portion of the spring member, the cavity including an endportion adjacent the second end of the spring member, that end portionhaving a diameter smaller than the outside diameter of at least oneconvolution adjacent the second end of the spring member, the oneconvolution having a thread-forming edge along the outside peripherythereof such that rotation of the housing relative to the spring memberin the direction of installation will form a complementary thread in thehousing at the endportion to establish a threaded engagement betweenthat one convolution and the housing for transmitting installationtorque from the housing to the spring member.

The invention will be more fully understood, while still further objectsand advantages will become apparent, in the following detaileddescription of a preferred embodiment illustrated in the accompanyingdrawing. in which:

FIG. 1 is a plan view of a wire connector constructed in accordance withthe invention;

FIG. 2 is an end view of the wire connector;

FIG. 3 is an enlarged cross-sectional view taken along line 3-3 of FIG.1, together with a pair of electrical wires to be connected;

FIG. 4 is a view similar to FIG. 3, but with the wire connectorinstalled over the ends of the electrical wires. 1

Referring now to the drawing, and especially to FIGS. 1 through 3thereof, a wire connector constructed in accordance with the inventionis illustrated generally at 10 and has a housing 12 of relatively rigiddielectric material and a helically coiled spring member 14 fixed withinthe housing 12.

Housing 12 is of unitary construction and preferably is molded of asynthetic resin having desirable strength and toughness as well as therequisite electrical insulating properties. The housing is generally inthe form of a shell providing an internal bore or cavity 16 extendingfrom an open end 18 of the housing 12 to a closed end 20, a first part22 of the cavity 16 having an internal diameter great enough to receivethe ends of insulated electrical wires 24 and 26 to be placed within thewire connector and a second part 28 having an internal contour generallycomplementary to the external configuration of the helically coiledspring member 14, as will be explained in more detail hereinafter.

As outlined above, it is the function of a wire connector to securefirmly together a plurality of wires to establish a fast mechanicaljoint as well as a good electrical connection between the ends of thewires. The wires 24 and 26 are received within the wire connector 10through the open end 18 and are engaged by the spring member 14 bytwisting the wire connector to longitudinally advance the wires fromopen end 18 toward closed end 20, the engagement of spring member 14with the wires 24 and 26 being likened to a screwthreaded engagement.

In order to facilitate grasping and turning of the wire connector duringinstallation, the exterior of the housing 12 is provided with a pair ofcars 30 extending laterally outwardly. Ears 30 may be grippedconveniently by an operators fingers to enhance the ability of theoperator to twist the wire connector as the connector is advanced alongthe wires 24 and 26. The particular configuration of the ears 30 alsoserves to indicate the direction of rotation for installation, asillustrated by the arrow in FIG. 2.

Turning now to FIG. 4, as well as to FIGS. 1 through 3, spring member 14is provided with a plurality of convolutions 32. In order to grip thewires 24 and 26 firmly. the convolutions 32 have an internal edge 34 forpermanently deforming the wires by pressing a groove into the wires asthe wire connector is advanced over the ends of the wires duringinstallation. The spring member 14 is generally tapered from a largerdiameter at first end 36 to a smaller diameter at second end 38, thetaper being established by intermediate convolutions of consecutivelysmaller diameter extending along the central portion 40 of the springmember lying between the first and second ends 36 and 38, respectively.These intermediate convolutions are resiliently expansible so that avariety of wire sizes can be accommodated by resilient dilation of theconvolutions as the spring member 14 is advanced over the wires. Thedifference between the inside diameter of the cavity 16 adjacent theintermediate convolutions and the outside diameter of the intermediateconvolutions along the central portion 40 of the spring member 14establishes a clearance space 42 which accommodates the desiredresilient expansion of the intermediate convolutions. The ability oftheintermediate convolutions to expand and contract resiliently also servesto maintain a relatively constant gripping force upon the Wires throughcycles of heating and cooling which may be encountered during service.

In order to couple the spring member 14 for rotation with the housing 12during installation of the wire connector 10 over wires 24 and 26, therelative dimensions of the cavity 16 adjacent closed end and theconvolution at the second end 38 of the spring member are such that aninterference fit is established between the housing and the springmember adjacent the second end 38 sufficient to transmit the requisitedriving torque for installation. Thus, the inside diameter of the endportion 44 of the cavity 16 is smaller than the outside diameter of theconvolution 46 ofthe spring memher.

As best seen in FIG. 3, prior to installation. end portion 44 has nothread complementary toconvolution 46 but merely receives convolution 46at the entrance to end portion 44 with a slight interference fit. Theconvolution 46 has a thread-forming edge 48 along the outside peripheryof the convolution so that relative rotation between the housing 12 andthe spring member 14, as the housing is rotated in the direction ofinstallation, will establish a complementary thread 50 in end portion 44and thus provide a threaded engagement between the convolution 46 andthe housing 12. As such relative rotation is continued, a deeper thread50 is established in the wall of the housing by a combination ofpressing and cutting of the housing material by the end portion of thespring member at end 38 in response to installation of the wireconnector 10 upon the wires 24 and 26. In order to assure the formationof such a deeper thread and thus enhance the coupling between thehousing and the spring member, the end portion 44 of the cavity 26 istapered toward a smaller diameter at the end wall 52 of the housing 12.Relative rotation between the housing and the spring member will stopwhen the end 38 of the spring member bears againstthe end wall 52 of thehousing. Continued turning of the housing will merely thread the wires24 and 26 deeper into the spring member 14.

Preferably, the wall thickness of the end wall 52 and.

the wall thickness of the wall of the housing along end portion 44 isgreater than the predetermined wall thickness of the remainder of thehousing so as to reinforce the housing in the vicinity where the springmember is coupled to the housing. Additionally, the thickness of the endwall 52 is great enough to withstand the thrust of the end 54 of wire 24against the end wall. Furthermore, by limiting the inside diameter ofthe convolution 46 at the small end 38 of the spring member 14 to thatwhich will not permit the passage through convolution 46 of a wirehaving sufficient column strength to pierce the end wall 52 of thehousing. such failure of the housing is prevented.

Manufacture and assembly of the component parts of the wire connector 10is simplified by the abovedescribed structure. Thus, the spring member14 need merely be placed within the housing 12 wherein the spring memberis retained by place by lip 56 which projects into the cavity 16 at thelarge end 36 of the tion. Manufacture ofthe housing is simplified inthat no special structure, such as abutments or threads, is required atthe closed end 20 of the housing, nor is any thread required adjacentthe lip 56 or anywhere along the cavity 16. Assembly is simplified inthat angular orientation of the spring member 14 relative to the housing12 is not critical when the spring member is inserted into the housing.

It is to be understood that the above detailed description of apreferred embodiment is provided by way of example only. Various detailsof design and construction may be modified without departing from thetrue spirit and scope of the invention as set forth in the appendedclaims.

The embodiments of the invention in which as exclusive property orprivilege is claimed are defined as follows:

1. As an article of manufacture, a wire connector for securing aconnection between electrical wire ends by rotational installation overthe wire ends, said wire connector comprising:

a helically coiled spring member extending longitudinally from a largerdiameter first and toward a smaller diameter second end, said memberbeing generally tapered longitudinally along a central portion thereofbetween said ends and having a plurality of convolutions;

a housing having a wall of relatively rigid insulating material. saidhousing having a cavity containing said spring member, the cavity havinga configuration generally complementary to the external configuration ofthe spring member with the relative dimensions of the cavity and thespring member providing a clearance space between the housing and thecentral portion of the spring member, said wall having a predeterminedwall thickness along the portion of the length thereof corresponding tothe tapered longitudinal central portion of the spring member;

said housing including a lip projecting into the cavity adjacent thefirst end of the spring member and retaining the spring member withinthe cavity prior to said rotational installation, and an end walladjacent the second end of the spring member; and

coupling means for transmitting installation torque from the housing tothe spring member, upon said rotational installation, and subsequentlyprecluding relative longitudinal movement between the spring member andthe housing, said coupling means consisting of:

an unthreaded end portion of said cavity, said end portion having agiven inside diameter at the outside periphery of at least oneconvolution adjacent said second end of the spring member, the thicknessof the wall at the unthreaded end portion of the cavity and at said endwall being greater than said predetermined wall thickness; and

a thread-forming edge along the outside periphery of at least said oneconvolution adjacent the second end of the spring member, saidthreadforming edge having an outside diameter larger than the giveninside diameter of the unthreaded end portion of the cavity by an amountgreat enough to enable, upon rotation of the housing relative to thespring member in the direction of said installation, the formation of acomplementary thread of sufficient depth in the thicker housing wall atsaid unthreaded end portion to establish a threaded engagement betweenthe said one convolution and said housing of a strength great enough totransmit said installation torque and preclude said longitudinalmovement;

said one convolution having an inside diameter small enough to precludethe passage through the convolution of a wire having sufficient columnstrength to pierce the end wall.

1. As an article of manufacture, a wire connector for securing aconnection between electrical wire ends by rotational installation overthe wire ends, said wire connector comprising: a helically coiled springmember extending longitudinally from a larger diameter first end towarda smaller diameter second end, said member being generally taperedlongitudinally along a central portion thereof between said ends andhaving a plurality of convolutions; a housing having a wall ofrelatively rigid insulating material, said housing having a cavitycontaining said spring member, the cavity having a configurationgenerally complementary to the external configuration of the springmember with the relative dimensions of the cavity and the spring memberproviding a clearance space between the housing and the central portionof the spring member, said wall having a predetermined wall thicknessalong the portion of the length thereof corresponding to the taperedlongitudinal central portion of the spring member; said housingincluding a lip projecting into the cavity adjacent the first end of thespring member and retaining the spring member within the cavity prior tosaid rotational installation, and an end wall adjacent the second end ofthe spring member; and coupling means for transmitting installationtorque from the housing to the spring member, Upon said rotationalinstallation, and subsequently precluding relative longitudinal movementbetween the spring member and the housing, said coupling meansconsisting of: an unthreaded end portion of said cavity, said endportion having a given inside diameter at the outside periphery of atleast one convolution adjacent said second end of the spring member, thethickness of the wall at the unthreaded end portion of the cavity and atsaid end wall being greater than said predetermined wall thickness; anda thread-forming edge along the outside periphery of at least said oneconvolution adjacent the second end of the spring member, saidthread-forming edge having an outside diameter larger than the giveninside diameter of the unthreaded end portion of the cavity by an amountgreat enough to enable, upon rotation of the housing relative to thespring member in the direction of said installation, the formation of acomplementary thread of sufficient depth in the thicker housing wall atsaid unthreaded end portion to establish a threaded engagement betweenthe said one convolution and said housing of a strength great enough totransmit said installation torque and preclude said longitudinalmovement; said one convolution having an inside diameter small enough topreclude the passage through the convolution of a wire having sufficientcolumn strength to pierce the end wall.